Probable Cause

Incident Synopsis
While a hot air dryer was being used to free a coupling in a hydrogen cryostat (an apparatus used to maintain constant low temperatures), a flash fire occurred. The H2 cryostat was being dismantled.

Causes
The temperature at the center of the cryostat was sufficiently low to liquefy air. The prescribed requirements for purging and bringing the cryostat to room temperature were circumvented. The H2 - air mixture was formed and ignition was assumed to be a spark from an open filament of the dryer.

Incident Synopsis
A technician was welding a cable suspended over a stainless steel H2 instrument line. During the welding process, two holes were accidentally burned through the hydrogen tubing. The operator heard a hissing sound and closed the valve, but the hydrogen had already ignited and it burned his hand while he was feeling for a leak.

Cause
A short during welding caused the pinholes in the tubing containing the gaseous H2.

A hydrogen explosion occurred in an emergency battery container used to transfer fuel elements. The container had five emergency power batteries. Damage was incurred by the explosion.

Cause

The H2 concentration in the container increased because the battery charger had been left on charge. In addition, the container was placed in an un-ventilated airlock. Ignition of the H2-air mixture was believed to be caused by the relays and micro switches activated when the airlock door was opened.

A battery that was left on a charger over a given weekend was used to start a gasoline power generator. This battery was connected in series with another battery and the connection on the negative post was hand tightened. When an attempt was made to start the generator, the battery exploded on approximately the fifth click of the starter solenoid. No damage was done to any equipment or facilities and no one was injured.

The most probable cause of the accident was the severe overcharging of the battery (64 hours at 20 amp/hour). This charging created hydrogen, which combined with air or oxygen and an ignition source to form the explosion. One source of ignition could have been the loosely attached connection to the battery terminal. Another possible source may have been an view more

A hydrogen explosion occurred in an Uninterruptible Power Source (UPS) battery room. The explosion blew a 400 ft2 hole in the roof, collapsed numerous walls and ceilings throughout the building, and significantly damaged a large portion of the 50,000 ft2 building. Fortunately, the computer/data center was vacant at the time and there were no injuries.

The facility was formerly a large computer/data center with a battery room and emergency generators. The company vacated the building and moved out the computer equipment; however the battery back-up system was left behind. The ventilation for the battery room appeared to be tied into a hydrogen monitoring system. The hydrogen sensor was in alarm upon emergency responders arriving at the scene (post-explosion). 911 callers view more

A person working in a hydrogen lab unknowingly closed the wrong hydrogen valve and proceeded to loosen a fitting in one of the hydrogen gas lines. The pressure in the 1/4"-diameter hydrogen line was approximately 110 psig. Hydrogen escaped from the loosened fitting and the pressure release resulted in the tubing completely detaching and falling to the floor. The person noted seeing a white stream around the hydrogen jet leak. The person noted a color change and noise change as the leak ignited (this happened in a matter seconds and he did not have a chance to react). The person left the lab and pushed the emergency stop button. Someone else pulled the fire alarm. Both of these actions were designed to close the main hydrogen solenoid (shutoff) valve. The local emergency response view more

Lessons Learned Corner

H2 Tools is intended for public use. It was built, and is maintained, by the Pacific Northwest National Laboratory with funding from the DOE Office of Energy Efficiency and Renewable Energy's Fuel Cell Technologies Office.